1. Field of the Invention
The present invention relates to a tornado generating method and apparatus for artificially generating a tornado in a fluid, and utilizing the characteristics of the tornado to suck and eliminate a contaminated fluid by the tornado.
2. Description of the Related Art
For a conventional tornado generating method, as shown in FIG. 1, a method is known, wherein a barrel a which is substantially enclosed is provided with blow-out nozzles b, air is blown from these blow-out nozzles along a side wall c of the barrel a and sucked from a suction port d at the same time, thereby allowing a tornado t to be generated. This is a so-called in-pipe tornado, and is the oldest one of known tornado generating methods.
For another tornado generating method, as shown in FIG. 2, a method is known wherein a box e with an open front for use as a hood is provided with two suction ports d on the top surface thereof and with blow-out pipes g on both sides of an open portion f, air is blown from the two blow-out pipes g to form air curtains h and sucked from the two suction ports d at the same time, thereby allowing two tornadoes t to be formed in the box e. This method allows persons to work even when smoke, a hazardous gas and a large amount of dust exist in a box e serving as a hood.
In addition, for another tornado generating method, as shown in FIG. 3, a method is known wherein four blow-out pipes g for blowing air to form air curtains h are arranged in parallel with each other such that their blowing directions form the same rotation, spiral flows i are formed by the wake flow action of the air curtains h from the blow-out pipes g, and a suction port d is provided on at least one end of both ends of the axis direction of the blow-out pipes g to be located in the axial direction of the spiral flows i, and a shield plate j is provided in at least other of the both end surfaces. In this method, air is blown from the blow-out pipes g and sucked from the suction port d at the same time, thereby generating a tornado t toward the suction port d in the space surrounded by the air curtains h (disclosed in U.S. Pat. No. 5,096,467 owned by the Applicant).
For another tornado generating method, as shown in FIG. 4, a method is known wherein a curved plate k is provided with a shielding plate j on both ends thereof and with a suction port d on at least one end of the shielding plate j, and a blow-out pipe g is provided on one end of the curved direction of the curved plate k and the direction in which air is blown from the blow-out pipe g is directed within 90 degrees from a plane l connecting both ends of the curved plate k to the opposite side of the curved plate k. In this method, air is blown from the blow-out pipe g and sucked from the suction port d at the same time to form a spiral flow i between an air curtain h and the curved plate k, thereby generating a artificial tornado horizontally toward the suction port d (disclosed in J. P. Application No.2-290452 by the Applicant).
The conventional tornado generating methods mentioned above, however, effectually utilizes wall surfaces and air blows to surround a predetermined space for forcedly generating a spiral flow (vortex) in the space and sucking air from the axis direction of the vortex, thereby generating a tornado. In particular, according to the concept of Rankine's vortex, the vortex includes an outside free vortex and a forced vortex inside thereof, and the conventional tornado generating methods utilize wall sides and air blows to give energy to the outside free vortex and drive the inside forced vortex which is the core of a tornado.
From this point of view, the tornado generating methods mentioned above will hereinafter be examined.
In the tornado generating method as shown in FIG. 1, air is blown from the blow-out nozzles b along the side wall c of the barrel a to forcedly form a spiral flow and air is blown from the suction port d to generate the tornado t. Thus, the inside forced vortex which is the core of the tornado is driven by the outside free vortex.
In the tornado generating method as shown in FIG. 2, the box e and the air curtains h from two blow-out pipes g on both sides of the open surface of the box e substantially enclose the box e. In this method, air is sucked from the suction ports d to forcedly changes the air curtains h into two spiral flows with different rotational directions to generate two tornadoes t. Thus, the inside forced vortex which is the core of the tornado is driven by the outside free vortex similar to the method in FIG. 1.
In the tornado generating method as shown in FIG. 3, four air curtains h from four blow-out pipes g, a shielding plate j and a floor surface form an enclosed space. In this method, the spiral flow i is forcedly formed by the wake flow action of the air curtains h in the enclosed space and air is sucked from the suction port d, thereby generating the tornado t. Thus, the inside forced vortex which is the core of the tornado is driven by the outside free vortex similar to the method in FIGS. 1, 2.
In the tornado generating method as shown in FIG. 4, the curved plate k, the shielding plate j provided on both ends thereof and the air curtain h from the blow-out pipe g provided at one end of the curved plate k form a substantially enclosed space. In this method, the spiral flow i is forcedly formed by the wake flow action of the air curtain h in the enclosed space and the action of the curved plate k, i.e. the action that an air flow generated by sucking air from the suction port d becomes a rotationnal flow along the curved plate k, and then air is sucked from the suction port d, thereby generating the tornado t. Thus, the inside forced vortex which is the core of the tornado is driven by the outside free vortex similar to the method in FIGS. 1, 2 and 3.
The prior art examples as shown in FIGS. 1, 2 and 3 are used for each purpose and sufficiently satisfy their purposes. All of the above-mentioned prior art examples, however, involve forming enclosed spaces with wall surfaces and air curtains or the like and driving the inside forced vortex which is the core of the tornado by the outside free vortex, in some places, so that it is difficult to surround a predetermined space with wall surfaces or the like. Furthermore, in order to forcedly generate the spiral flow in the enclosed space and change the spiral flow into the tornado and continue to generate them, any person or object is not allowed to be in at least the tornado portion. Thus, a large scale of partitions and various equipment are required at present, so that it is difficult to realize such apparatus.